Reduction of Risk Factors for ACL Re-injuries using an Innovative Biofeedback Approach Project Summary Nearly 1 in 60 adolescent athletes will suffer ACL injuries. Approximately 90% of these injured athletes will undergo an ACL reconstruction at an estimated annual cost of $3 billion. While reconstruction and subsequent rehabilitation allow these athletes to return to sports, they have a 15 fold increased risk of secondary ACL injuries, a tear of the ACL graft or the contralateral ACL. As a result, development of an intervention to reduce the incidence of secondary ACL tears would meet a critical need. One area in which existing interventions might be improved is through an increased emphasis on correcting asymmetric movement patterns?a known risk factor for secondary injury. Thus, our long-term objective is to decrease the number of secondary ACL tears by decreasing side-to-side movement and loading asymmetry. The modification of post-operative rehabilitation to focus on movement and loading symmetry with shift the rehabilitation paradigm. Specifically, we propose to evaluate a novel biofeedback training program that focuses on altering loading and movement patterns to improve symmetry and overall lower extremity mechanics in a group of 40 (20 control, 20 intervention) adolescent ACL reconstructed patients. There are two core hypotheses of this study: 1) biofeedback training will decrease known risk factors for secondary ACL injuries immediately following the biofeedback program and these changes will be retained 6 week after the completion of the biofeedback program; and 2) we will be able to recruit and enroll 40 patients and retain 80% of the patients through the end of the follow-up assessment demonstrating the feasibility of the biofeedback intervention. Implementation of a biofeedback program prior to returning to dynamic athletic activities could improve physical performance outcomes, decrease secondary injury risk factors and ultimately decrease the long-term joint degeneration and development of osteoarthritis that has been associated with ACL reconstruction. Ultimately this work will lead to additional investigations to definitively determine the impact of this novel biofeedback program, which could shift the post-operative rehabilitation paradigm following ACL reconstruction to improve long-term joint health in these adolescent patients.